This invention relates generally to electronic engine controls. More particularly the invention relates to a strategy that is employed by an electronic engine control to develop a certain torque request for an engine in accordance with a certain torque control strategy for controlling engine torque. The invention is useful in the operation of internal combustion engines, especially diesel engines, that power automotive vehicles, such as trucks.
Because of known relationships between torque and speed that are characteristic of a particular engine, the control of engine torque by control of fuel input to the engine also has control implications for engine speed. Accordingly, a control system and strategy for a diesel engine may include a torque/speed control strategy. The occurrence of certain events while a diesel-engine-powered vehicle is being driven may impact the engine torque/speed control strategy, and therefore it may be desirable to take the occurrence of such events into account in the torque/speed control system and strategy. Examples of such events are traction-control-related events and transmission-related events. A traction- control-related event involves a change in traction while a transmission-related event involves a transmission gear change.
Accordingly, one generic aspect of the invention relates to a control system for controlling a diesel engine powering a motor vehicle. The control system comprises: a processor programmed to provide a preset value of maximum allowable engine torque data that is processed for control of the engine during non-occurrence of a vehicle event that would otherwise call for changing the preset value to a different value; a first data source providing data defining a current maximum limit for fueling the engine; a second data source providing data defining a torque request for the engine; and a third data source providing data distinguishing between the occurrence and non-occurrence of a vehicle event calling for change in the value of the maximum allowable engine torque data from the preset value to a different value. When the third data source data indicates occurrence of a vehicle event calling for change in the value of the maximum allowable engine torque data from the preset value to a different value, the processor processes the data from the first data source and the data from the second data source to develop data that is then processed by the processor as the value of the maximum allowable engine torque data instead of the preset value.
Another generic aspect of the invention relates to a method for controlling a diesel engine powering a motor vehicle. The method comprises programming a processor to provide a preset value of maximum allowable engine torque data that is processed for control of the engine during non-occurrence of a vehicle event that would otherwise call for changing the preset value to a different value. The method further comprises developing data defining a current maximum limit for fueling the engine; developing data defining a torque request for the engine; and developing data distinguishing between the occurrence and nonoccurrence of a vehicle event calling for change in the value of the maximum allowable engine torque data from the preset value to a different value. When the data distinguishing between the occurrence and non-occurrence of a vehicle event calling for change in the value of the maximum allowable engine torque data from the preset value to a different value indicates occurrence of a vehicle event calling for change in the value of the maximum allowable engine torque data from the preset value to a different value, the data defining a. current maximum limit for fueling the engine and the data defining a torque request for the engine are processed to develop data that is then processed by the processor as the value of the maximum allowable engine torque data instead of the preset value.
Further aspects will be set forth hereinafter in the disclosure and various claims.
The foregoing, along with further features and advantages of the invention, will be seen in the following disclosure of a presently preferred embodiment of the invention depicting the best mode contemplated at this time for carrying out the invention. The disclosure includes drawings, as now briefly described.